Partially addresses #47424.

Root container repository is a images repository that had been created
before 9.1, before we introduced multi-level images support.

Because we do not have yet two way communication between container
registry and GitLab, we need to eagerly create a new container
repository objects in database. We now do that after user/build
successfully authenticates a push action using auth service.

This is important because method `empty?` is triggered when validation
happens, and we don't want to make API request to registry when record
is validated.

Container repository can be empty - no tags or blogs is OK.

[ci skip]

[ci skip]

Conflicts:
	db/schema.rb

  - Fixes project, container_image and tag deletion
  - Removed container_images_repository

[ci skip]

  - Adds Registry events API endpoint
  - Adds container_images_repository and container_images models
  - Changes JWT authentication to allow multi-level scopes
  - Adds services for container image maintenance